Add SignextLowering pass to wasm-opt
#1280
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| // This pass will then remove any `signext` instructions in order that the resulting | ||
| // Wasm binary is compatible with older versions of `pallet-contracts` which do not | ||
| // support the `signext` instruction. | ||
| .add_pass(Pass::SignextLowering) |
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Since paritytech/substrate#14565 we do allow sign_extension in smart contracts on the pallet side. Shouldn't we make this pass optional for the cargo-contract so that the users of the newer versions of pallet-contracts could still opt in to have signext instructions in their contracts?
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I am aware, and I did consider making this optional. I decided against it because removing them by default means that both old and new versions of pallet_contracts will be supported with this, so will make users and our lives easier if the resulting wasm is compatible with as wide a range of target nodes as possible.
I assume the majority of node implementations currently are using an older version of pallet_contracts which does not support signext.
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I see. Could adding smth like --allow-signext to the cargo-contract contract build so that wasm_opt runs without the pass, be an option then?
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Yes, it would be preferable to do that if the user really does want signext instructions.
It would be interesting to do some analysis to the benefits or otherwise of contracts with or without the signext lowering pass. Could check for differences in contract sizes and gas efficiency.
* Add `SignextLowering` pass to `wasm-opt` (#1280) * Add `SignextLowering` pass to `wasm-opt` * Remove check for Rust version (cherry picked from commit 756aa38) * Update wasm-opt * Cargo.lock * Enable Wasm sign_ext (#1189) * Enable Wasm sign_ext * Bump substrate crates * Add warning when building with new rustc * Stable toolchain * Revert "Stable toolchain" This reverts commit aa2a2e6. --------- Co-authored-by: Andrew Jones <ascjones@gmail.com> * Cargo.lock * Remove version check * WIP updating subxt * Updating subxt --------- Co-authored-by: Alexander Theißen <alex.theissen@me.com>
Fixes #1239.
As suggested here: #1239 (comment), this will allow a newer toolchain >
1.69to be used to deploy to older versions ofpallet-contractswhich do not yet supportsignext.It does so by adding an extra
wasm-optpass which "lowers" anysignextinstructions to mvp only features.Tested that a contract built with Rust >=
1.70can be uploaded to a node which does not supportsignext.If it does work we can then consider either backporting this to a
3.2.0release, or just going ahead and doing a4.0.0release.